Conventional concrete block walls are laid up by a time-consuming difficult procedure which involves troweling a layer of concrete mortar onto a level concrete or stone base or the like, or the top of a course of previously laid blocks and then setting blocks one at a time in the mortar layer, in each instance also applying mortar to the end walls of each block to join the blocks together. This procedure is continued until the required number of courses are laid. Great care must be taken to keep each course perfectly horizontal and straight. Few people have the skill to carry out such a procedure in a competent manner, therefore the cost of such construction is always high.
Various types of interlocking blocks have been devised in the past to facilitate the construction of block walls and other structures. Most such blocks have been very expensive to produce since the interlocking portions, usually grooves or protrusions, are normally cut into the blocks after they have been formed by molding. Moreover, it is difficult to maintain the required tight tolerances for accurate construction of large walls or other structures through the molding and cutting steps. The prior blocks often required additional finishing or grinding steps to meet the required tolerances.
Interlocking mortarless building blocks overcoming many of these deficiencies are described in U.S. Pat. Nos. 3,888,060 and 4,640,071. Those blocks have been used successfully for many years. These blocks are assembled in courses, with the block joints staggered and continuous vertical open cells into which reinforcing bars and wet concrete can be inserted. While highly effective, these blocks require that the reinforcing bar be inserted in lower courses, with blocks in later courses lifted over the ends of the reinforcing bar as the structure advances and wet concrete is periodically poured into the cells containing the reinforcing bar.
Thus installing blocks over the reinforcing bar can be a significant problem with tall structures.
Therefore, there is a continuing need for improvements in mortarless building block systems to permit lower cost block manufacture, and lower cost and more rapid structure assembly from the blocks. It would also be desirable to be able to provide an improved mortarless building block system featuring improved adaptability, strength and economy. The design of the block should be such that it can be readily molded and released from the forming mold with full detail preserved, obviating any subsequent reshaping, finishing, etc. Further, the block should be easily strengthened with reinforcing materials, if needed, and be capable of being fabricated in a full array of sizes and shapes.